Chiriquitoxin is a potent neurotoxin (LD50 about 8 micrograms/kg i.p. mouse) related to, but not identical with, tetrodotoxin which has been discovered in the skin of the colorful Costa Rican frog Atelopus chiriquiensis. These studies are aimed at isolating, purifying, determining the chemical structure and characterizing the pharmacology of chiriquitoxin. BIBLIOGRAPHIC REFERENCES: Pharmacology and Chemistry of Chiriquitoxin, A New Tetrodotoxin-like Substance from the Costa Rican Frog Atelopus chiriquiensis. F.A. Fuhrman, G.J. Fuhurman, Y.H. Kim and H.S. Mosher, Proc. West. Pharmacol. Soc., 19, 381-384 (1976). Neutoxins from three species of California Goby: Clevelandia ios, Acanthogobius flavimanus and Gillichthys mirabilis. K.S. Elam, F.A. Fuhrman, Y.H. Kim and H.S. Mosher. Toxicon, 15: 45-49, (1977).